In rotary machines, such as turbines, non-contact measurement is used. For example, in Patent Document 1, torque is measured by projecting laser light to a reflective sticker affixed to a rotor, detecting the reflected light with an optical sensor, and signal-processing the detection values. Also, in blade vibration measurement and clearance measurement in turbines, desired measurement values are obtained by projecting laser light to blades or a reflection target, detecting the reflected light with an optical sensor to detect passing time of the blades or the reflection target, and calculating data on the time difference.